1. Field of the Invention
The present invention relates to a mask which is used in a vapor deposition method or the like, a method of manufacture thereof, a device for manufacture therefore, and the like.
Priority is claimed on Japanese Patent Application Nos. 2003-061355, 2003-061356, and 2003-061357, filed 7 Mar. 2003, and to Japanese Patent Application 2004-036621, filed 13 Feb. 2004, the contents of which are incorporated herein by reference.
2. Background Art
As a self luminescent type display which is used for making a display device which is yet thinner than a liquid crystal display, attention is being attracted, as the next era of technology, to organic EL displays which employ organic EL (electroluminescent) elements (luminescent elements which are manufactured by providing a luminescent layer which is made from an organic material between a positive electrode and a negative electrode). As the luminescent layer material for an organic EL element, there are low molecular weight organic materials and high molecular weight organic materials, and it is known to manufacture a luminescent layer which is made from such a type of low molecular weight organic material by a vapor deposition process. When thus manufacturing a luminescent layer by a vapor deposition process, the direct formation of a thin layer pattern upon the surface upon which the layer is to be made in correspondence to the picture elements is performed by using a mask plate (which is a mask plate which is provided with through holes corresponding to the thin layer pattern which is to be created, and which generally is made from a metal such as stainless steel or the like). In order to respond to demands for very miniature picture elements, it has become practiced to utilize a mask plate which is made very thin, and with a pattern in which very miniature through holes are opened at narrow intervals, and, in order to prevent deformation such as warping or bending or the like accompanying reduction of the strength of such a mask plate, there is a technique, such as for example the one disclosed in Japanese Unexamined Patent Application, First Publication No. 2001-237073, of reinforcing the mask plate by joining it to a substrate.
Due to demands for a display with very fine picture elements, there is a requirement to manufacture a luminescent layer with no so called bleeding. For this, it is necessary to approach together the mask plate and the surface upon which the layer is to be formed as closely as possible, so that the luminescent material does not insinuate itself upon the rear side of the mask plate (the surface which opposes the surface upon which the layer is to be formed), and so as to make the shape of the luminescent layer be roughly the same as the shape of the through holes which are formed in the mask. However, it is difficult to make the thickness of an adhesive for joining together the substrate and the mask plate by curing from the liquid state (the thickness of the junction region) constant. Accordingly, it is not possible to reduce the distance between the mask plate and the surface upon which the layer is to be formed, and there arises the problem that the luminescent material may insinuate itself onto the rear side of the mask plate, thus forming a luminescent layer which has bleeding.
Furthermore, in the manufacture of the above described mask, normally, a method is employed in which the substrate is mounted upon a stage device or the like, and the mask plate is adjusted from its upper side and is joined to it with a photo-curing adhesive, but, if the mask plate is formed from an optically opaque material, it is not possible to cure the photo-curing adhesive by illuminating it with light from the mask side. Due to this, the necessity arises of illuminating it with light from the substrate side. However, in order to illuminate the light from the underside of the stage device, the problem arises that the stage device becomes more complicated and larger in size; and furthermore, when illuminating light from the substrate side while relatively shifting the substrate and the mask plate, there may be the difficulty of deviation of the relative position of the substrate and the mask plate, since the photo-curing adhesive is not cured.
Furthermore, even if a mask is used in which the junction of the mask plate with the substrate is reinforced, when performing vapor deposition processing for the luminescent material, the temperature of the mask is elevated, and the problem may occur that the position of the through holes may deviate due to thermal expansion of the mask, so that unacceptable deviation of the thin film pattern may take place.
The present invention has been made in the light of this type of situation, and takes as its objectives to provide a mask, a method of manufacturing a mask, a device for manufacturing a mask, a method of manufacturing a layer of luminescent material, an electro-optical device, and an electronic device, which can vapor-deposit a luminescent layer with high precision, by easily making the distance between a substrate and a mask plate constant, furthermore by joining together the mask plate, which constitutes a light interception member, and the substrate at high precision without using a special device, and moreover by reducing positional deviation between the pattern on the mask when performing vapor deposition.